By Margaret Munro
CanWest News Service

Thursday, October 5, 2006

MACKENZIE RIVER DELTA, N.W.T. - The sun is beating down on an icy bluff, sending chunks of ancient permafrost crashing to the ground.

Rivers of mud stream off the exposed permafrost, cracking and dripping in the 20 Celsius late-summer heat. Enormous ice wedges that have grown metres long over the eons protrude from the top of the bluff like giant fangs.

"Is this cool or what?" asks Scott Dallimore of the Geological Survey of Canada as he scrambles out of a helicopter in his hip waders. He heads for the steel grey bluff to take a closer look. But the melted permafrost is like quicksand and stops him in his tracks.

"We first found this exposure two years ago," says Dallimore. The contorted pattern of the exposed permafrost suggests it might be hundreds of thousands of years old.

"It's been frozen like this forever."

But not for long. The bluff, on an island that is one of the anchor sites for the proposed $7-billion Mackenzie Valley pipeline, is melting away at the rate of 10 to 20 metres a year.

So are hundreds of other permafrost ridges and cliffs across Canada's North. Geoscientist Rob Bowen, working with Dallimore to assess gases escaping from the frozen ground, likens permafrost to a "sleeping giant" that could awaken with potentially catastrophic consequences.

One nightmare scenario suggests that as permafrost warms, it might belch out enough methane -- a greenhouse gas -- to trigger runaway global warming. There is some evidence such giant burps have occurred in the past. Permafrost also contains large stores of mercury, a neurotoxin, and massive amounts of soil carbon, which could speed global warming.

But it's the water melting out of the upper layer of permafrost that's of immediate concern to engineers and northern planners. The so-called "active" layer -- the top metres or two of permafrost that melts every summer and then refreezes -- is becoming more active, playing havoc with the region's infrastructure. And vulnerable permafrost cliffs and ridges are melting, sending enormous blocks of the frozen ground sliding and toppling into Arctic seas and rivers.

Permafrost covers close to 20 per cent of the planet and almost half of Canada -- down to a depth of 700 metres in parts of the Western Arctic. There is so much permafrost underground and beneath the Arctic seas that scientists say it's not going to disappear soon.

Gases could be liberated even if the "deep" permafrost warms just a few degrees, Dallimore says. And there is evidence the frozen ground is warming.

Geographer Christopher Burn of Carleton University runs North America's longest running permafrost monitoring experiments on the Mackenzie Delta. "Climate change is happening, there is no question in my mind. I see it on the ground and I see it in the ground," Burn says.

He points to the willow trees, lupines and shrubs that have moved onto his expansive research site, which used to be barren tundra.

But it is the change underground that makes the site so significant. Fifteen metres below ground, the temperature has risen 1.5 degrees to minus 6.5 C since 1970, says Burn, who has a growing collection of thermometers and gauges dangling down drill holes.

"When temperatures are rising 15 metres underground, it's not variation, it's a change," he says.

Informant: NHNE


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